Display system with optical elements for in-coupling multiplexed light streams

ABSTRACT

Architectures are provided for selectively incoupling one or more streams of light from a multiplexed light stream into a waveguide. The multiplexed light stream can have light with different characteristics (e.g., different wavelengths and/or different polarizations). The waveguide can comprise in-coupling elements that can selectively couple one or more streams of light from the multiplexed light stream into the waveguide while transmitting one or more other streams of light from the multiplexed light stream.

PRIORITY CLAIM

This application is a continuation of U.S. application Ser. No.17/200,697 filed on Mar. 12, 2021, which is a continuation of U.S.application Ser. No. 16/369,890 filed on Mar. 29, 2019, which is acontinuation of U.S. application Ser. No. 15/182,528 filed on Jun. 14,2016, which claims the benefit of priority under 35 USC § 119(e) of U.S.Provisional App. No. 62/175,994 filed on Jun. 15, 2015 and of U.S.Provisional App. No. 62/180,551 filed on Jun. 16, 2015. Each of theabove-identified applications is incorporated by reference herein in itsentirety.

INCORPORATION BY REFERENCE

This application incorporates by reference in its entirety each of thefollowing U.S. patents and patent applications: U.S. Pat. No. 6,334,960,issued on Jan. 1, 2002, titled “Step and Flash Imprint Technology;” U.S.Pat. No. 6,873,087, issued on Mar. 29, 2005, titled “High-PrecisionOrientation, Alignment and Gap control Stages for Imprint LithographyProcesses;” U.S. Pat. No. 6,900,881, issued on May 31, 2005, titled“Step and Repeat Imprint Lithography;” U.S. Pat. No. 7,070,405, issuedon Jul. 4, 2006, titled “Alignment Systems for Imprint Lithography;”U.S. Pat. No. 7,122,482, issued on Oct. 17, 2006, titled “Methods forFabricating Patterned Features Utilizing Imprint Lithography;” U.S. Pat.No. 7,140,861, issued on Nov. 28, 2006, titled “Compliant Hard Templatefor UV Imprinting;” U.S. Pat. No. 8,076,386, issued on Dec. 13, 2011,titled “Materials for Imprint Lithography;” U.S. Pat. No. 7,098,572,issued on Aug. 29, 2006, titled “Apparatus to Control Displacement of aBody Spaced Apart from a Surface;” U.S. application Ser. No. 14/641,376filed on Mar. 7, 2015; U.S. application Ser. No. 14/555,585 filed onNov. 27, 2014; U.S. application Ser. No. 14/690,401 filed on Apr. 18,2015; U.S. application Ser. No. 14/212,961 filed on Mar. 14, 2014; andU.S. application Ser. No. 14/331,218 filed on Jul. 14, 2014.

BACKGROUND Field

The present disclosure relates to virtual reality and augmented realityimaging and visualization systems.

Description of the Related Art

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” experiences, wherein digitally reproduced images or portionsthereof are presented to a user in a manner wherein they seem to be, ormay be perceived as, real. A virtual reality, or “VR”, scenariotypically involves presentation of digital or virtual image informationwithout transparency to other actual real-world visual input; anaugmented reality, or “AR”, scenario typically involves presentation ofdigital or virtual image information as an augmentation to visualizationof the actual world around the user. For example, referring to FIG. 1 ,an augmented reality scene (1) is depicted wherein a user of an ARtechnology sees a real-world park-like setting (6) featuring people,trees, buildings in the background, and a concrete platform (1120). Inaddition to these items, the user of the AR technology also perceivesthat he “sees” a robot statue (1110) standing upon the real-worldplatform (1120), and a cartoon-like avatar character (2) flying by whichseems to be a personification of a bumble bee, even though theseelements (2, 1110) do not exist in the real world. Because the humanvisual perception system is complex, it is challenging to produce a VRor AR technology that facilitates a comfortable, natural-feeling, richpresentation of virtual image elements amongst other virtual orreal-world imagery elements.

Systems and methods disclosed herein address various challenges relatedto VR and AR technology.

SUMMARY

The systems, methods and devices of the disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

In some embodiments, a display system is provided. The display systemincludes a waveguide; and an image injection device configured to directa multiplexed light stream into the waveguide. The multiplexed lightstream includes a plurality of light streams having different lightproperties. The waveguide includes in-coupling optical elementsconfigured to selectively in-couple a first of the streams of lightwhile being transmissive to one or more other streams of light. In someembodiments, the waveguide is part of a stack of waveguides, which caninclude a second waveguide including in-coupling optical elementsconfigured to selectively turn a second of the streams of light whilebeing transmissive to one or more other streams of light. In someembodiments, the in-coupling optical elements of the waveguide areconfigured to transmit at least one of the streams of light to thein-coupling optical elements of the second waveguide.

Various methods of manufacturing liquid crystal devices including jetdepositing liquid crystal material on a substrate and using an imprintpattern to align the molecules of the liquid crystal are describedherein. Using the methods described herein, devices including one orseveral layers of liquid crystal material can be manufactured. Liquidcrystal devices manufactured using the methods described herein caninclude liquid crystal gratings including features and/or patterns thathave a size less than about a few microns. Liquid crystal devicesmanufactured using the methods described herein can also include liquidcrystal features and/or patterns that have a size less than thewavelength of visible light and may comprise what are referred to asPancharatnam-Berry Phase Effect (PBPE) structures, metasurfaces, ormetamaterials. In some cases, the small patterned features in thesestructures can be about 10 nm to about 100 nm wide and about 100 nm toabout 1 micron high. In some cases, the small patterned features inthese structures can be about 10 nm to about 1 micron wide and about 10nm to about 1 micron high. Structures for manipulating light, such asfor beam steering, wavefront shaping, separating wavelengths and/orpolarizations, and combining different wavelengths and/or polarizationscan include liquid crystal gratings with metasurface, otherwise referredto herein as metamaterials liquid crystal gratings or liquid crystalgratings with Pancharatnam-Berry Phase Effect (PBPE) structures. Liquidcrystal gratings with PBPE structures can combine the high diffractionefficiency and low sensitivity to angle of incidence of liquid crystalgratings with the high wavelength sensitivity of the PBPE structures.Using the various methods of manufacturing described herein, liquidcrystal gratings with PBPE structures can be mass-produced which may notbe possible using the existing methods of disposing PBPE structures onliquid crystal materials. The methods discussed herein can also be usedto fabricate polarizers that are more transparent than existingpolarizers.

An innovative aspect of the subject matter disclosed herein includes adisplay system comprising a waveguide and an image injection deviceconfigured to direct a multiplexed light stream into the waveguide. Themultiplexed light stream provided by the image injection device cancomprise a plurality of light streams having different light properties.The waveguide comprises in-coupling optical elements that are configuredto selectively in-couple a first of the streams of light while beingtransmissive to one or more other streams of light. The in-couplingoptical elements can comprise at least one of diffractive structures,liquid crystal material, meta-surfaces, metamaterials, PBPE structures,liquid crystal polarization grating comprising PBPE structures or liquidcrystal polarization grating comprising metasurface. The in-couplingoptical elements can be switchable between transmissive and activelylight redirecting states. Various embodiments of the waveguide can beincluded in an eyepiece of a head mounted display.

In various embodiments of the display system, the waveguide can be apart of a stack of waveguides. The stack of waveguides can include asecond waveguide comprising in-coupling optical elements that can beconfigured to selectively turn a second of the streams of light whilebeing transmissive to one or more other streams of light. In suchembodiments, the in-coupling optical elements of the waveguide can beconfigured to transmit at least one of the streams of light to thein-coupling optical elements of the second waveguide.

The light streams can have different wavelengths, differentpolarizations, or combinations thereof. In various embodiments, theimage injection device can be configured to simultaneously provide allof the light streams of the plurality of light streams to the waveguide.In various embodiments, the image injection device can be configured toprovide at least some of the light streams of the plurality of lightstreams to the waveguide at different times. The image injection devicecan be a scanning optical fiber. In various embodiments, the imageinjection device can comprise a light modulating device.

In various embodiments, the waveguide and/or the second waveguide cancomprise out-coupling elements that are configured to output thein-coupled first stream of light propagating in the waveguide. Theout-coupling elements can comprise a first group of light redirectingelements configured to increase dimensions of an eyebox along at leastone axis. The out-coupling element can further comprise a second groupof light redirecting elements configured to increase dimensions of theeyebox along an axis that is orthogonal to the at least one axis.

Another innovative aspect of the subject matter disclosed hereinincludes a display system comprising a plurality of stacked waveguidesand an image injection device. The image injection device is configuredto direct a multiplexed light stream into the plurality of stackedwaveguides. The multiplexed light stream comprises a plurality of lightstreams having different light properties. Each waveguide in theplurality of stacked waveguides comprises in-coupling optical elements.Each waveguide is configured to selectively in-couple one or more of theplurality of light streams while being transmissive to one or more otherof the plurality of light streams. The plurality of stacked waveguidescan be included in an eyepiece of a head mounted display. Each waveguidecomprises out-coupling elements that are configured to output thein-coupled one or more of the plurality of light streams propagating inthe waveguide.

The in-coupling optical elements can comprise at least one ofdiffractive structures, liquid crystal material, meta-surfaces,metamaterials, PBPE structures, liquid crystal polarization gratingcomprising PBPE structures or liquid crystal polarization gratingcomprising metasurface. In various embodiments, the in-coupling opticalelements can be switchable between transmissive and actively lightredirecting states. The different light properties can have differentwavelengths respectively, different polarizations respectively, orcombinations thereof. The image injection device can be configured tosimultaneously provide all of the light streams of the plurality oflight streams to the waveguide. The image injection device can beconfigured to provide at least some of the light streams of theplurality of light streams to the waveguide at different times. Invarious embodiments, the image injection device can be a scanningoptical fiber. In some embodiments, the image injection device cancomprise a light modulating device.

An innovative aspect of the subject matter disclosed herein includes adisplay system comprising a waveguide; and an image injection deviceconfigured to direct a multiplexed light stream into the waveguide. Themultiplexed light stream can comprise a plurality of light streamshaving different light properties. The waveguide comprises firstin-coupling optical elements configured to selectively in-couple a firstof the stream of light while being transmissive to one or more otherstreams of light. In some embodiments, the waveguide can comprise secondin-coupling optical elements configured to selectively in-couple asecond of the stream of light while being transmissive to one or moreother streams of light. In some other embodiments, the waveguide cancomprise third in-coupling optical elements configured to selectivelyin-couple a third of the stream of light while being transmissive to oneor more other streams of light. In various embodiments, the first,second or third in-coupling optical elements can include a liquidcrystal layer comprising a metasurface. Various embodiments of thewaveguide can be included in an eyepiece of a head mounted display.

Details of one or more embodiments of the subject matter described inthis specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a user's view of augmented reality (AR) through an ARdevice.

FIG. 2 illustrates an example of wearable display system.

FIG. 3 illustrates a conventional display system for simulatingthree-dimensional imagery for a user.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes.

FIGS. 5A-5C illustrate relationships between radius of curvature andfocal radius.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user.

FIG. 7 shows an example of exit beams outputted by a waveguide.

FIG. 8A schematically illustrates a perspective view of an example ofthe delivery of multiplexed image information into one or morewaveguides.

FIG. 8B schematically illustrates a perspective view of another exampleof the delivery of multiplexed image information into multiplewaveguides.

FIG. 8C schematically illustrates a top-down view of the display systemof FIG. 8B.

FIG. 8D illustrates the display system of FIG. 8C, with lightredirecting elements to out-couple light from each waveguide.

FIG. 8E illustrates the display system of FIG. 8B including an imageinjection device comprising a light modulation device for providing x-ypixel information.

FIG. 9A illustrates an embodiment of a method of fabricating a liquidcrystal device.

FIGS. 9B and 9C illustrate embodiments of imprint templates that can beused to fabricate liquid crystal devices in accordance with the methoddescribed in FIG. 9A above or FIG. 9D below.

FIG. 9D illustrates another embodiment of a method of fabricating aliquid crystal device.

FIG. 9E, FIG. 9F, FIG. 9G and FIG. 9H illustrate various embodiments ofliquid crystal devices that can be manufactured using the methodsdescribed in FIG. 9A or 9D.

FIG. 9I illustrates an embodiment of a resist layer imprinted with apattern as described in the method described in FIG. 9D.

FIG. 9J illustrates a first imprint structure having discrete dropletsor sections that are oriented along a first direction and a secondimprint structure having discrete droplets or sections that are orientedalong a second direction that can be combined to produce optical deviceswith complex grating patterns.

FIG. 9K and FIG. 9L illustrate different polarizer configurations thatcan be fabricated using the jet deposition and imprinting methodsdescribed herein.

FIG. 9M illustrates an embodiment of a waveguide plate having a lightentrance surface and a light exit surface that can change thepolarization state of incident light.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

Embodiments disclosed herein include optical systems, including displaysystems, generally. In some embodiments, the display systems arewearable, which may advantageously provide a more immersive VR or ARexperience. For example, displays containing a stack of waveguides maybe configured to be worn positioned in front of the eyes of a user, orviewer. In some embodiments, two stacks of waveguides, one for each eyeof a viewer, may be utilized to provide different images to each eye.

FIG. 2 illustrates an example of wearable display system (80). Thedisplay system (80) includes a display (62), and various mechanical andelectronic modules and systems to support the functioning of thatdisplay (62). The display (62) may be coupled to a frame (64), which iswearable by a display system user or viewer (60) and which is configuredto position the display (62) in front of the eyes of the user (60). Insome embodiments, a speaker (66) is coupled to the frame (64) andpositioned adjacent the ear canal of the user (in some embodiments,another speaker, not shown, is positioned adjacent the other ear canalof the user to provide for stereo/shapeable sound control). The display(62) is operatively coupled (68), such as by a wired lead or wirelessconnectivity, to a local data processing module (70) which may bemounted in a variety of configurations, such as fixedly attached to theframe (64), fixedly attached to a helmet or hat worn by the user,embedded in headphones, or otherwise removably attached to the user (60)(e.g., in a backpack-style configuration, in a belt-coupling styleconfiguration).

The local processing and data module (70) may comprise a processor, aswell as digital memory, such as non-volatile memory (e.g., flashmemory), both of which may be utilized to assist in the processing,caching, and storage of data. The data include data a) captured fromsensors (which may be, e.g., operatively coupled to the frame (64) orotherwise attached to the user (60)), such as image capture devices(such as cameras), microphones, inertial measurement units,accelerometers, compasses, GPS units, radio devices, and/or gyros;and/or b) acquired and/or processed using remote processing module (72)and/or remote data repository (74), possibly for passage to the display(62) after such processing or retrieval. The local processing and datamodule (70) may be operatively coupled by communication links (76, 78),such as via a wired or wireless communication links, to the remoteprocessing module (72) and remote data repository (74) such that theseremote modules (72, 74) are operatively coupled to each other andavailable as resources to the local processing and data module (70).

In some embodiments, the remote processing module (72) may comprise oneor more processors configured to analyze and process data and/or imageinformation. In some embodiments, the remote data repository (74) maycomprise a digital data storage facility, which may be available throughthe internet or other networking configuration in a “cloud” resourceconfiguration. In some embodiments, all data is stored and allcomputations are performed in the local processing and data module,allowing fully autonomous use from a remote module.

The perception of an image as being “three-dimensional” or “3-D” may beachieved by providing slightly different presentations of the image toeach eye of the viewer. FIG. 3 illustrates a conventional display systemfor simulating three-dimensional imagery for a user. Two distinct images74 and 76, one for each eye 4 and 6, are outputted to the user. Theimages 74 and 76 are spaced from the eyes 4 and 6 by a distance 10 alongan optical or z-axis parallel to the line of sight of the viewer. Theimages 74 and 76 are flat and the eyes 4 and 6 may focus on the imagesby assuming a single accommodated state. Such systems rely on the humanvisual system to combine the images 74 and 76 to provide a perception ofdepth for the combined image.

It will be appreciated, however, that the human visual system is morecomplicated and providing a realistic perception of depth is morechallenging. For example, many viewers of conventional “3-D” displaysystems find such systems to be uncomfortable or may not perceive asense of depth at all. Without being limited by theory, it is believedthat viewers of an object may perceive the object as being“three-dimensional” due to a combination of vergence and accommodation.Vergence movements (i.e., rolling movements of the pupils toward or awayfrom each other to converge the lines of sight of the eyes to fixateupon an object) of the two eyes relative to each other are closelyassociated with focusing (or “accommodation”) of the lenses of the eyes.Under normal conditions, changing the focus of the lenses of the eyes,or accommodating the eyes, to change focus from one object to anotherobject at a different distance will automatically cause a matchingchange in vergence to the same distance, under a relationship known asthe “accommodation-vergence reflex.” Likewise, a change in vergence willtrigger a matching change in accommodation, under normal conditions. Asnoted herein, many stereoscopic or “3-D” display systems display a sceneusing slightly different presentations (and, so, slightly differentimages) to each eye such that a three-dimensional perspective isperceived by the human visual system. Such systems are uncomfortable formany viewers, however, since they, among other things, simply providedifferent presentations of a scene, but with the eyes viewing all theimage information at a single accommodated state, and work against the“accommodation-vergence reflex.” Display systems that provide a bettermatch between accommodation and vergence may form more realistic andcomfortable simulations of three-dimensional imagery.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes. With reference toFIG. 4A, objects at various distances from eyes 4 and 6 on the z-axisare accommodated by the eyes (4, 6) so that those objects are in focus.The eyes 4 and 6 assume particular accommodated states to bring intofocus objects at different distances along the z-axis. Consequently, aparticular accommodated state may be said to be associated with aparticular one of depth planes (14), such that objects or parts ofobjects in a particular depth plane are in focus when the eye is in theaccommodated state for that depth plane. In some embodiments,three-dimensional imagery may be simulated by providing differentpresentations of an image for each of the eyes (4, 6), and also byproviding different presentations of the image corresponding to each ofthe depth planes.

The distance between an object and the eye (4 or 6) can change theamount of divergence of light from that object, as viewed by that eye.FIGS. 5A-5C illustrates relationships between distance and thedivergence of light rays. The distance between the object and the eye(4) is represented by, in order of decreasing distance, R1, R2, and R3.As shown in FIGS. 5A-5C, the light rays become more divergent asdistance to the object decreases. As distance increases, the light raysbecome more collimated. Stated another way, it may be said that thelight field produced by a point (the object or a part of the object) hasa spherical wavefront curvature, which is a function of how far away thepoint is from the eye of the user. The curvature increases withdecreasing distance between the object and the eye (4). Consequently, atdifferent depth planes, the degree of divergence of light rays is alsodifferent, with the degree of divergence increasing with decreasingdistance between depth planes and the viewer's eye 4. While only asingle eye (4) is illustrated for clarity of illustration in FIGS. 5A-5Cand other figures herein, it will be appreciated that the discussionsregarding eye (4) may be applied to both eyes (4 and 6) of a viewer.

Without being limited by theory, it is believed that the human eyetypically can interpret a finite of depth planes to provide depthperception. Consequently, a highly believable simulation of perceiveddepth may be achieved by providing, to the eye, different presentationsof an image corresponding to each of these limited number of depthplanes.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user. A display system 1000 includes a stack ofwaveguides, or stacked waveguide assembly, (178) that may be utilized toprovide three-dimensional perception to the eye/brain using a pluralityof waveguides (182, 184, 186, 188, 190). In some embodiments, thedisplay system (1000) is the system (80) of FIG. 2 , with FIG. 6schematically showing some parts of that system (80) in greater detail.For example, the waveguide assembly (178) may be integrated into thedisplay (62) of FIG. 2 .

With continued reference to FIG. 6 , the waveguide assembly (178) mayalso include a plurality of features (198, 196, 194, 192) between thewaveguides. In some embodiments, the features (198, 196, 194, 192) maybe lens. The waveguides (182, 184, 186, 188, 190) and/or the pluralityof lenses (198, 196, 194, 192) may be configured to send imageinformation to the eye with various levels of wavefront curvature orlight ray divergence. Each waveguide level may be associated with aparticular depth plane and may be configured to output image informationcorresponding to that depth plane. Image injection devices (200, 202,204, 206, 208) may be utilized to inject image information into thewaveguides (182, 184, 186, 188, 190), each of which may be configured,as described herein, to distribute incoming light across each respectivewaveguide, for output toward the eye 4. Light exits an output surface(300, 302, 304, 306, 308) of the image injection devices (200, 202, 204,206, 208) and is injected into a corresponding input edge (382, 384,386, 388, 390) of the waveguides (182, 184, 186, 188, 190). In someembodiments, a single beam of light (e.g. a collimated beam) may beinjected into each waveguide to output an entire field of clonedcollimated beams that are directed toward the eye (4) at particularangles (and amounts of divergence) corresponding to the depth planeassociated with a particular waveguide.

In some embodiments, the image injection devices (200, 202, 204, 206,208) are discrete displays that each produce image information forinjection into a corresponding waveguide (182, 184, 186, 188, 190,respectively). In some other embodiments, the image injection devices(200, 202, 204, 206, 208) are the output ends of a single multiplexeddisplay which may, e.g., pipe image information via one or more opticalconduits (such as fiber optic cables) to each of the image injectiondevices (200, 202, 204, 206, 208).

A controller 210 controls the operation of the stacked waveguideassembly (178) and the image injection devices (200, 202, 204, 206,208). In some embodiments, the controller 210 includes programming(e.g., instructions in a non-transitory medium) that regulates thetiming and provision of image information to the waveguide (182, 184,186, 188, 190) according to, e.g., any of the various schemes disclosedherein. In some embodiments, the controller may be a single integraldevice, or a distributed system connected by wired or wirelesscommunication channels. The controller 210 may be part of the processingmodules (70 or 72) (FIG. 2 ) in some embodiments.

The waveguides (182, 184, 186, 188, 190) may be configured to propagatelight within each respective waveguide by total internal reflection(TIR). The waveguides (182, 184, 186, 188, 190) may each be planar, withmajor top and bottom surfaces and edges extending between those majortop and bottom surfaces. In the illustrated configuration, thewaveguides (182, 184, 186, 188, 190) may each include light redirectingelements (282, 284, 286, 288, 290) that are configured to redirectlight, propagating within each respective waveguide, out of thewaveguide to output image information to the eye 4. A beam of light isoutputted by the waveguide at locations at which the light propagatingin the waveguide strikes a light redirecting element. The lightredirecting elements (282, 284, 286, 288, 290) may be reflective and/ordiffractive optical features. While illustrated disposed at the bottommajor surfaces of the waveguides (182, 184, 186, 188, 190) for ease ofdescription and drawing clarity, in some embodiments, the lightredirecting elements (282, 284, 286, 288, 290) may be disposed at thetop and/or bottom major surfaces, and/or may be disposed directly in thevolume of the waveguides (182, 184, 186, 188, 190). In some embodiments,the light redirecting elements (282, 284, 286, 288, 290) may be formedin a layer of material that is attached to a transparent substrate toform the waveguides (182, 184, 186, 188, 190). In some otherembodiments, the waveguides (182, 184, 186, 188, 190) may be amonolithic piece of material and the light redirecting elements (282,284, 286, 288, 290) may be formed on a surface and/or in the interior ofthat piece of material.

With continued reference to FIG. 6 , as discussed herein, each waveguide(182, 184, 186, 188, 190) is configured to output light to form an imagecorresponding to a particular depth plane. For example, the waveguide(182) nearest the eye may be configured to deliver collimated light, asinjected into such waveguide (182), to the eye (4). The collimated lightmay be representative of the optical infinity focal plane. The nextwaveguide up (184) may be configured to send out collimated light whichpasses through the first lens (192; e.g., a negative lens) before it canreach the eye (4); such first lens (192) may be configured to create aslight convex wavefront curvature so that the eye/brain interprets lightcoming from that next waveguide up (184) as coming from a first focalplane closer inward toward the eye (4) from optical infinity. Similarly,the third up waveguide (186) passes its output light through both thefirst (192) and second (194) lenses before reaching the eye (4); thecombined optical power of the first (192) and second (194) lenses may beconfigured to create another incremental amount of wavefront curvatureso that the eye/brain interprets light coming from the third waveguide(186) as coming from a second focal plane that is even closer inwardtoward the person from optical infinity than was light from the nextwaveguide up (184).

The other waveguide layers (188, 190) and lenses (196, 198) aresimilarly configured, with the highest waveguide (190) in the stacksending its output through all of the lenses between it and the eye foran aggregate focal power representative of the closest focal plane tothe person. To compensate for the stack of lenses (198, 196, 194, 192)when viewing/interpreting light coming from the world (144) on the otherside of the stacked waveguide assembly (178), a compensating lens layer(180) may be disposed at the top of the stack to compensate for theaggregate power of the lens stack (198, 196, 194, 192) below. Such aconfiguration provides as many perceived focal planes as there areavailable waveguide/lens pairings. Both the light redirecting elementsof the waveguides and the focusing aspects of the lenses may be static(i.e., not dynamic or electro-active). In some alternative embodiments,they may be dynamic using electro-active features.

With continued reference to FIG. 6 , the light redirecting elements(282, 284, 286, 288, 290) may be configured to both redirect light outof their respective waveguides and to output this light with theappropriate amount of divergence or collimation for a particular depthplane associated with the waveguide. As a result, waveguides havingdifferent associated depth planes may have different configurations oflight redirecting elements (282, 284, 286, 288, 290), which output lightwith a different amount of divergence depending on the associated depthplane. In some embodiments, as discussed herein, the light redirectingelements (282, 284, 286, 288, 290) may be volumetric or surfacefeatures, which may be configured to output light at specific angles.For example, the light redirecting elements (282, 284, 286, 288, 290)may be volume holograms, surface holograms, and/or diffraction gratings.Light redirecting elements, such as diffraction gratings, are describedin U.S. patent application Ser. No. 14/641,376, filed Mar. 7, 2015,which is incorporated by reference herein in its entirety. In someembodiments, the features (198, 196, 194, 192) may not be lenses;rather, they may simply be spacers (e.g., cladding layers and/orstructures for forming air gaps).

In some embodiments, the light redirecting elements (282, 284, 286, 288,290) are diffractive features that form a diffraction pattern, or“diffractive optical element” (also referred to herein as a “DOE”).Preferably, the DOE's have a relatively low diffraction efficiency sothat only a portion of the light of the beam is deflected away towardthe eye (4) with each intersection of the DOE, while the rest continuesto move through a waveguide via total internal reflection. The lightcarrying the image information is thus divided into a number of relatedexit beams that exit the waveguide at a multiplicity of locations andthe result is a fairly uniform pattern of exit emission toward the eye(4) for this particular collimated beam bouncing around within awaveguide.

In some embodiments, one or more DOEs may be switchable between “on”states in which they actively diffract, and “off” states in which theydo not significantly diffract. For instance, a switchable DOE maycomprise a layer of polymer dispersed liquid crystal, in whichmicrodroplets comprise a diffraction pattern in a host medium, and therefractive index of the microdroplets can be switched to substantiallymatch the refractive index of the host material (in which case thepattern does not appreciably diffract incident light) or themicrodroplet can be switched to an index that does not match that of thehost medium (in which case the pattern actively diffracts incidentlight).

FIG. 7 shows an example of exit beams outputted by a waveguide. Onewaveguide is illustrated, but it will be appreciated that otherwaveguides in the stack of waveguides (178) may function similarly.Light (400) is injected into the waveguide (182) at the input edge (382)of the waveguide (182) and propagates within the waveguide (182) by TIR.At points where the light (400) impinges on the DOE (282), a portion ofthe light exits the waveguide as exit beams (402). The exit beams (402)are illustrated as substantially parallel but, as discussed herein, theymay also be redirected to propagate to the eye (4) at an angle (e.g.,forming divergent exit beans), depending on the depth plane associatedwith the waveguide (182). It will be appreciated that substantiallyparallel exit beams may be indicative of a waveguide that corresponds toa depth plane at a large distance (e.g., optical infinity) from the eye(4). Other waveguides may output an exit beam pattern that is moredivergent, which would require the eye (4) to accommodate to a closerdistance to bring it into focus on the retina and would be interpretedby the brain as light from a distance closer to the eye (4) than opticalinfinity.

Part I. Multiplexed Image Information

With reference again to FIG. 6 , utilizing a dedicated image injectiondevice (200, 202, 204, 206, or 208) for each waveguide (182, 184, 186,188, or 190) may be mechanically complex and may require a large volumeto accommodate all of the image injection devices and their relatedconnections. A smaller form factor may be desirable for someapplications, such as wearable displays.

In some embodiments, a smaller form factor may be achieved by using asingle image injection device to inject information into a plurality ofthe waveguides. The image injection device delivers multiple imageinformation streams (also referred to herein as information streams) tothe waveguides, and these information streams may be considered to bemultiplexed. Each waveguide includes in-coupling optical elements thatinteract with the information streams to selectively in-couple imageinformation from a particular information stream into that waveguide. Insome embodiments, the in-coupling optical elements selectively redirectlight from a particular information stream into its associatedwaveguide, while allowing light for other information streams tocontinue to propagate to other waveguides. The redirected light isredirected at angles such that it propagates through its associatedwaveguide by TIR. Thus, in some embodiments, a single image injectiondevice provides a multiplexed information stream to a plurality ofwaveguides, and each waveguide of that plurality of waveguides has anassociated information stream that it selectively in-couples usingin-coupling optical elements.

The selective interaction between the in-coupling optical elements andthe information streams may be facilitated by utilizing informationstreams with different optical properties. For example, each informationstream may be formed by light of different colors (differentwavelengths) and/or different polarizations (preferably differentcircular polarizations). In turn, the in-coupling optical elements areconfigured to selectively redirect light of a particular polarizationand/or of one or more particular wavelengths, thereby allowing aspecific correspondence, e.g., one-to-one correspondence, between aninformation stream and a waveguide. In some embodiments, the in-couplingoptical elements are diffractive optical elements configured toselectively redirect light based upon the properties of that light,e.g., the wavelength and/or polarization of that light.

In some embodiments, each image injection device provides imageinformation to a plurality of two, three, four, or more waveguides byproviding, respectively, two, three, four, or more information streamsto that plurality of waveguides. In some embodiments, multiple suchimage injection devices may be used to provide information to each ofmultiple pluralities of waveguides.

With reference now to FIG. 8A, an example of the delivery of multiplexedimage information into one or more waveguides is illustratedschematically in a perspective view. A stack 3000 includes waveguides3002 and 3004, which include in-coupling optical elements 3012 and 3014,respectively. In some embodiments, the waveguides 3002 and 3004 may besubstantially planar plates, each having a front and rear major surfaceand edges extending between these front and rear major surfaces. Forexample, waveguide 3002 has front major surface 3002 a and rear majorsurface 3002 b. The major surfaces of the waveguides may include acladding layer (not illustrated) to facilitate the TIR of light withineach waveguide. In some embodiments, the stack 3000 of waveguidescorresponds to the stack 178 of FIG. 6 and may be utilized to replacethe stack 178 in the display systems disclosed herein.

With continued reference to FIG. 8A, light streams A and B havedifferent light properties, e.g., different wavelengths and/or differentpolarizations (preferably different circular polarizations). The lightstreams A and B include distinct image information streams. Light A andB and their information streams are propagated through optical conduit3024 (e.g., an optical fiber) as a multiplexed information stream to animage injection device 3021. The image injection device injects light3040 (containing the multiplexed information stream as combined lightstreams A and B) into the waveguide stack 3000.

In some embodiments, the image injection device 3021 includes anactuator 3020 (such as a piezoelectric actuator) that is coupled to anoptical fiber 352, which may be used to scan the fiber tip of the fiber352 across an area of the stack 3000. Examples of such scanning fiberimage injection devices are disclosed in U.S. patent application Ser.No. 14/641,376, filed Mar. 7, 2015, which is incorporated by referenceherein in its entirety. In some other embodiments, the image injectiondevice 3021 may be stationary and, in some embodiments, may direct lighttowards the stack 3000 from multiple angles.

In some embodiments, each waveguide includes in-coupling opticalelements. For example, waveguide 3002 includes in-coupling opticalelements 3012, and waveguide 3004 includes in-coupling optical elements3014. The in-coupling optical elements 3012 and 3014 are configured toselectively redirect one of light streams A and B. For example,in-coupling optical elements 3012 may selectively redirect at least aportion of light stream A to in-couple that light stream into the lightguide 3002. The in-coupled portion of light stream A propagates throughthe waveguide 3002 as light 3042. In some embodiments, the light 3042propagates through the waveguide 3002 by TIR off the major surfaces 3002a and 3002 b of that waveguide. Similarly, in-coupling optical elements3014 may selectively redirect at least a portion of light stream B toin-couple that light stream into the light guide 3004. The in-coupledportion of light stream B propagates through the waveguide 3004 as light3044. In some embodiments, the light 3044 propagates through thewaveguide 3004 by TIR off the major surfaces 3004 a and 3004 b of thatwaveguide.

As illustrated, in some embodiments, the multiplexed light stream 3040includes both light streams A and B simultaneously, and light stream Amay be in-coupled to waveguide 3002 while light stream B is in-coupledto waveguide 3004, as discuss above. In some other embodiments, lightstreams A and B may be provided to the waveguide stack 3000 at differenttimes. In such embodiments, only a single waveguide may be utilized toreceive these information streams, as discussed herein. In either case,the light streams A and B may be coupled to the optical conduit 3024 bythe optical coupler 3050. In some embodiments, the optical coupler 3050may combine light streams A and B for propagation through the opticalconduit 3024.

With continued reference to FIG. 8A, in some embodiments, optics 3030may be disposed between the image injection device 3021 and thein-coupling optical elements 3012 and 3014. The optics 3030 may include,e.g., lens that facilitating directing light rays onto the variousin-coupling optical elements 3012 and 3014, e.g., by focusing the lightonto in-coupling optical elements 3012 and 3014. In some embodiments,the optics are part of the image injection device 3021 and may be, e.g.,a lens at the end of the image injection device 3021. In someembodiments, optics 3030 may be omitted completely.

It will be appreciated that the in-coupling optical elements 3012 and3014 are configured to selectively redirect the light streams A and Bbased upon one or more light properties that differ between those lightstreams. For example, light stream A may have a different wavelengththan light stream B and the in-coupling optical elements 3012 and 3014may be configured to selectively redirect light based on wavelength.Preferably, the different wavelengths correspond to different colors,which can improve the selectivity of the in-coupling optical elementsrelative to using different wavelengths of the same color.

In some embodiments, light stream A may have a different polarizationthan light stream B and the in-coupling optical elements 3012 and 3014may be configured to selectively redirect light based on polarization.For example, the in-coupling optical elements 3012 and 3014 may beconfigured to selectively redirect light based on polarization. In someembodiments, the light streams A and B have different circularpolarization. In some embodiments, the light streams A and B may havemultiple differences in light properties, including, e.g., bothdifferent wavelengths and different polarizations.

In some embodiments, in-coupling optical elements 3012 and 3014 arediffractive optical elements, including diffractive gratings (e.g., agrating comprising liquid crystal such as a liquid crystal polarizationgrating). In some embodiments, the optical element may include ameta-surface (e.g., comprise a PBPE), such as a surface have a patternwith feature sizes on the order of one's or ten's of nanometers.Examples of suitable in-coupling optical elements 3012 and 3014 includethe optical elements 2000 b, 2000 d (FIG. 9A) and the optical elementsof FIGS. 9E-9H. Advantageously, such optical elements are highlyefficient at selectively redirecting light of different polarizationsand/or different wavelengths.

With reference now to FIG. 8B, another example of the delivery ofmultiplexed image information into multiple waveguides is illustratedschematically in a perspective view. It will be appreciated that thestack 3000 can include more than two waveguides, e.g., 4, 6, 8, 10, 12,or other numbers of waveguides, so long as image information can beadequately provided to individual waveguides and to a user's eyesthrough the stack 3000. The illustrated stack 3000 includes waveguides3006 and 3008 in addition to the waveguides 3002 and 3004. Thewaveguides 3006 and 3008 include in-coupling optical elements 3012 and3014, respectively. In some embodiments, the waveguides 3002, 3004,3006, and 3008 may be similar, except for the in-coupling opticalelements, which may each be configured to redirect and in-couple lighthaving different light properties. In some other embodiments,in-coupling optical elements for multiple waveguides may be similar. Itwill be appreciated that all the disclosure herein related to FIG. 8Aapply to FIG. 8B, except that the number of waveguides in FIG. 8B isgreater than in FIG. 8A.

With continued reference to FIG. 8B, light streams A, B, C, and D havedifferent light properties, e.g., different wavelengths and/or differentpolarizations (preferably different circular polarizations). Forexample, light streams A, B, C, and D may each include light ofdifferent wavelengths. In some other embodiments, various combinationsof different wavelengths and polarizations are possible. For example, Aand B may have similar wavelengths and different polarizations, and Cand D may have similar wavelengths and different polarizations, with Aand B different from C and D. Light streams A, B, C, and D arepropagated through optical conduit 3024 as a multiplexed informationstream to the image injection device 3021, which injects light 3040 ofthe multiplexed information stream into the waveguide stack 3000. Asdiscussed herein, the multiplexed information stream may include alllight streams simultaneously, or one or more of the light streams may bedirected to the stack 3000 at different times.

In some embodiments, each waveguide includes in-coupling opticalelements that selectively in-couple light into that waveguide. Forexample, waveguide 3002 includes in-coupling optical elements 3012,which may be configured to in-couple light stream A into that waveguide,so that it propagates by TIR in that waveguide as light 3042; waveguide3004 includes in-coupling optical elements 3014, which may be configuredto in-couple light stream B into that waveguide, so that it propagatesby TIR in that waveguide as light 3044; waveguide 3006 includesin-coupling optical elements 3016, which may be configured to in-couplelight stream C into that waveguide, so that it propagates by TIR in thatwaveguide as light 3046; and waveguide 3008 includes in-coupling opticalelements 3018, which may be configured to in-couple light stream D intothat waveguide, so that it propagates by TIR in that waveguide as light3048.

It will be appreciated that, in some embodiments, a single light stream(e.g., light stream A, B, C, or D) may be in-coupled to a singlewaveguide. In some other embodiments, multiple light streams may bein-coupled to the same waveguide. Preferably, in such an arrangement,the light streams are in-coupled at different times. In someembodiments, such temporally separated in-coupling may be achieved usingin-coupling optical elements that selectively turn light based onmultiple different light properties (e.g., multiple differentwavelengths or multiple different polarizations), while the imageinjection device provides the information streams for a particularwaveguide at different times. For example, both light streams A and Bmay be in-coupled to waveguide 3002, with the in-coupling opticalelements 3012 selectively in-coupling light streams A and B whileallowing light streams C and D to pass through, and with the lightstreams A and B providing light to the in-coupling optical elements 3012at different times while simultaneously providing light streams C and/orD to the in-coupling optical elements 3012. It will be appreciated thatone or more other waveguides may be similarly configured to in-couplemultiple light streams to those waveguides.

In some other embodiments, multiple light streams (e.g., light streams Aand B) may be provided simultaneously to the in-coupling opticalelements (e.g., in-coupling optical elements 3012), and the in-couplingoptical elements may be configured to change states to choose betweenin-coupling light stream A or B. For example, in some embodiments, thein-coupling optical elements may be a grating formed of liquid crystalmaterial disposed between electrodes (e.g., transparent electrodes suchas ITO). The liquid crystal may change states (e.g., orientations) withthe application of a voltage potential, with one state configured toselectively in-couple one light stream (e.g., light stream A) andanother state configured to be transparent to all light streams (e.g.,both light stream A and B). In some embodiments, another layer ofswitchable liquid crystal material, forming a different grating, may beprovided between electrodes, with one state configured to selectivelyin-couple a different light stream (e.g., light stream B) and anotherstate configured to be transparent to all light streams (e.g., bothlight stream A and B). In some other embodiments, both types of liquidcrystal material may be disposed on the same level, but in differentareas. The liquid crystal material may be configured such that when onetype of material is transparent to the light streams, the other typeselectively in-couples light of a particular light stream, and viceversa.

Now with reference to FIG. 8C, a top-down schematic view of the displaysystem of FIG. 8B is illustrated. The top-down view is taken lookingdown along a top edge of the stack 3000 of FIG. 8B. As illustrated, insome embodiments, portions of multiplexed light stream 3040 areselectively in-coupled into each of waveguides 3002, 3004, 3006, and3008 as in-coupled light 3042, 3044, 3046, and 3048.

As discussed herein, the waveguides may include light redirectingelements (e.g., light redirecting elements (282, 284, 286, 288, 290))that output or out-couple light, which has been propagating inside thewaveguide, so that the out-coupled light propagates towards the eyes 4of a viewer (FIG. 6 ). FIG. 8D illustrates the display system of FIG.8C, with light redirecting elements to out-couple light from eachwaveguide. For example, waveguide 3002 includes out-coupling lightredirecting elements 3062, waveguide 3004 includes out-coupling lightredirecting elements 3064, waveguide 3006 includes out-coupling lightredirecting elements 3066, and waveguide 3008 includes out-couplinglight redirecting elements 3068. In some embodiments, the out-couplinglight redirecting elements may include different groups of lightredirecting elements, each of which functions differently. For example,out-coupling light redirecting elements 3062 may include a first groupof light redirecting elements 3062 a and a second group of lightredirecting elements 3062 b. For example, light redirecting elements3062 b may be exit pupil expanders (EPEs; to increase the dimensions ofthe eye box in at least one axis), and light redirecting elements 3062 amay be orthogonal pupil expanders (OPEs; to increase the eye box in anaxis crossing, e.g., orthogonal to, the axis of the EPEs). EPEs and OPEsare disclosed in U.S. Provisional Patent Application No. 62/005,807,filed May 30, 2014, the entire disclosure of which is incorporated byreference herein.

It will be appreciated that images are formed by the waveguides usinginformation streams with encoded x-y pixel information. For example, theinformation streams of different colors may each indicate the intensityof light for a particular location on an x-y grid corresponding to thex-y pixel information for the image. Without being limited by theory, itwill also be appreciated that the matching of information streams towaveguides is achieved using the properties of light and is notnecessarily dependent upon the x-y pixel information provided by thatlight. Consequently, the x-y pixel information may be encoded at anysuitable location using any suitable device along the path of the lightbefore the light impinges on the in-coupling optical elements 3012,3014, 3016, and 3018.

In some embodiments, if a light source (e.g., LED or OLED) is pixilatedand is able to output light having the desired light properties (e.g.,desired wavelengths and/or polarizations), then an information streammay be formed having both the desired light properties and encoded x-ypixel information as it is emitted from the light source. In some otherembodiments, light having the desired light properties is passed througha light modulation device in which the x-y pixel information is encoded.FIG. 8E illustrates the display system of FIG. 8B and shows a lightmodulation device 3070 for providing x-y pixel information to the imageinformation stream. In some embodiments, the light modulation device3070 may be part of the image injection device 3021, and may beconfigured to provide image information using a scanning fiber, or oneor more stationary aperture display devices for providing imageinformation to the waveguides. In some embodiments, the light modulationdevice 3070 modifies the light as it passes through the device (e.g.,the intensity of the light may be modified by being passed through pixelelements having controllable variable light transmission). In some otherembodiments, the light modulation device may modify light by selectivelyredirecting (e.g., reflecting) light to propagate into the waveguidestack 3000. Examples of light modulation devices include transmissiveliquid crystal displays and micro-mirror devices (such as a “digitallight processing”, or “DLP” system, such as those available from TexasInstruments, Inc.).

Part II. Liquid Crystal Polarization Gratings with Pancharatnam-BerryPhase Effect (PBPE) Structures

This section relates to liquid crystals, polarization gratings, andPancharatnam-Berry Phase Effect (PBPE) structures, methods offabrication thereof as well as other structures and methods. In someembodiments, methods and apparatus are provided for manufacturing liquidcrystal grating structures that have high diffraction efficiency, lowsensitivity to angle of incident and high wavelength sensitivity.Various methods described herein include disposing a layer of liquidcrystal material using inkjet technology and using an imprint templateto align the liquid crystal material.

In some embodiments, the liquid crystals, polarization gratings, andPancharatnam-Berry Phase Effect (PBPE) structures disclosed in this PartII may be utilized to form light redirecting elements for the variouswaveguides of the waveguide stacks 178 (FIG. 6 ) or 3000 (FIGS. 8A-8E).For example, such liquid crystals, polarization gratings, andPancharatnam-Berry Phase Effect (PBPE) structures may advantageously beapplied to form the various in-coupling optical elements disclosedherein, including the in-coupling optical elements 3012, 3014, 3016,and/or 3018 (FIG. 8A-8E).

A variety of imaging systems and optical signal processing systems caninclude liquid crystal devices to control/manipulate an opticalwavefront, wavelength, polarization, phase, intensity, angle and/orother properties of light. Liquid crystals are partly ordered materialswhose molecules are often shaped like rods or plates or some other formsthat can be aligned along a certain direction. The direction along whichthe molecules of the liquid crystal are oriented can be manipulated byapplication of electromagnetic forces which can be used tocontrol/manipulate the properties of light incident on the liquidcrystal material.

Methods of manufacturing liquid crystal devices and certain resultingstructures are described herein.

The following detailed description is directed to certain embodimentsfor the purposes of describing the innovative aspects. However, theteachings herein can be applied in a multitude of different ways. Aswill be apparent from the following description, the innovative aspectsmay be implemented in any optical component or device that is configuredto manipulate one or more characteristics of incident light.

As discussed more fully below, innovative aspects described hereininclude fabricating liquid crystal devices using jet depositiontechnology. For example, in an embodiment of a method of manufacturing aliquid crystal device, a layer of liquid crystal material is depositedon a substrate using jet deposition technology (e.g., inkjettechnology). Surface relief features (e.g., PBPE structures) can beimprinted in the layer of the jet deposited liquid crystal materialusing a template. The surface relief features may be configured (e.g.,with particular spacing and/or heights) to achieve particular lightredirecting properties. In some other embodiments, imprinting can berepeated on different levels to produce successive layeredcross-sections that, in combination, can behave as volumetric featuressuch as exists in “bulk” volume-phase materials and devices. In variousembodiments, these surface relief features (and the successive layeredcross-sections) can be modeled as “Bragg” structures. Generally, suchstructures can be used to produce binary surface-relief features inwhich there exists a material-to-air interface, resist-to-air interface,resin-to-air interface or a liquid crystal material-to-air interfacethat produces diffraction, or a material-to-lower index resistinterface, resist-to-lower index resist interface, resin-to-lower indexresist interface or a liquid crystal material-to-lower index resistinterface that does the same. In these cases the gratings can be modeledas “raman-nath” structures, rather than Bragg structures. The moleculesof the liquid crystal material are aligned through the process ofimprinting due to the physical shape of the nanostructures and theirelectrostatic interaction with the liquid crystal (LC) material.Alignment of the liquid crystal layer using the imprint pattern isdiscussed in greater detail below.

In various embodiments, a layer of material, (e.g., a polymer), to serveas a photo-alignment layer, may be deposited using jet depositiontechnology (in which a jet or stream of material is directed onto asubstrate), e.g., via ink-jet onto a substrate or pre-coated substrate.The photo-alignment layer is patterned by nano-imprinting using atemplate incorporating the desired LC orientation pattern. In someembodiments, this pattern is a PBPE pattern, and the template,comprising a physical relief, may be made with interferometric and/orlithographic techniques. The template is lowered on to the soft polymerresin and UV light is used to cure the resin to a fixed state. In someembodiments, capillary action fills the template with the polymermaterial before it is cured. The template is retracted, leaving thepatterned, cured resin in place on the substrate. A second step, using adeposition process (e.g., jet or spin coating) applies a layer of LC(e.g., LC suspended in resin) on top of the photo-alignment layer. TheLC aligns to the photo-alignment layer pattern below it, and when thisoccurs, the resin is fixed in place using UV light, heat, or acombination of both. In some other embodiments, LC suspended in solvent(e.g., resin) is deposited (e.g., dispensed using jet or spin coating),and the template containing the nanoimprint pattern (e.g., a PBPEpattern) is lowered into contact with the LC material. to the LC takesup the relief profile of the template (e.g., by capillary action intothe openings in the template), and the LC material is fixed in placeusing a cure process (e.g., UV, heat or a combination of both). Theresulting structure may be used directly as a functional element, or insome cases, a low refractive index material can be deposited over theimprinted liquid crystal material to fill the interstitial areas betweenthe surface features imprinted in the liquid crystal material.

The low refractive index material can be configured as a planarizationlayer by tuning the viscoelastic and chemical properties of the liquidcrystals based resist (e.g., a liquid crystal polymer or a resincomprising a liquid crystal) or by contacting the top surface of the lowrefractive index material with a planarization imprint template (e.g., atemplate having a substantially planar surface). In some otherembodiments, the low refractive index material can be planarized by achemical and/or mechanical planarization process. The planarizationprocess is preferably chosen to form a planarized surface that issmooth, to reduce optical artifacts that may be caused by a roughsurface. Additional layers such as additional liquid crystal layers canbe deposited using the jet technology over the liquid crystal layer. ThePBPE structures in the different layers of liquid crystal can beconfigured to diffract, steer, and/or disperse or combine differentwavelengths of light. For example, red, green and blue wavelengths canbe diffracted, dispersed, or redirected along different directions bythe PBPE structures in the different liquid crystal layers.

The different liquid crystal layers are preferably formed with materialsthat provide sufficient structural stability and adhesion to allowlayers to be stacked over one another. In some embodiments, organic orinorganic imprint resist materials, including polymerizable materialsthat form optically transmissive cured structures, may be used. As anexample, the liquid crystal layers can include an acrylic liquid crystalformulation. Acrylic liquid crystal layers can provide adhesiveproperties that facilitate the stacking of layers on top of each other.

It will be appreciated that, as discussed herein both the liquid crystalmaterial and the low refractive index material may be flowablematerials. In some embodiments, these materials may be subjected to aprocess to immobilize them after contact with the imprint templates andbefore removing the contacting template. The immobilization process mayinclude a curing process, as discussed herein.

As another example, in another embodiment of a method of manufacturing aliquid crystal device, a layer of a photoresist material (e.g., a resinor a polymer) is deposited on a substrate. The deposition may beaccomplished by various deposition methods, including spin coating. Morepreferably, in some embodiments, the deposition is accomplished usingjet technology (e.g., inkjet technology). The photoresist is imprintedwith an imprint template or mold having surface relief features (e.g.,PBPE structures). A layer of liquid crystal material can be depositedusing jet technology on the imprinted layer of photoresist. Theimprinted photoresist layer can serve as an aligning layer to align themolecules of the liquid crystal material as it is deposited. Additionallayers such as additional liquid crystal layers or layers not comprisingliquid crystal can be deposited using the jet technology over the liquidcrystal layer. In various embodiments, a planarization layer can bedeposited over the deposited liquid crystal layer.

In embodiments discussed herein, different types of liquid crystalmaterials, such as, for example, doped liquid crystal, un-doped liquidcrystal, and other non-liquid crystal materials can be deposited usinginkjet technology. Inkjet technology can provide thin controlled (e.g.,uniform) thickness of the deposited liquid crystal layer orplanarization layer. Inkjet technology can also provide layers ofdifferent thickness such as layers of liquid crystal or other layershaving a different thickness in different areas on the surface and canaccommodate different pattern height and keep a constant residual layerthickness underneath the imprinted patterns. Inkjet technology isadvantageously capable of providing thin layers, for example betweenabout 10 nm and 1 micron; or between about 10 nm and about 10 microns inthickness and can reduce waste in comparison with other techniques suchas spin coating. The inkjet technology can facilitate deposition ofdifferent liquid crystal compositions on the same substrate. Inaddition, inkjet nano-imprinting can produce a very thin residual layerthickness. In the illustrated embodiments, the uniform area below theimprint pattern can correspond to the residual layer. PBPE and otherdiffractive structures can exhibit variable and sometimes enhancedperformance with very thin or zero residual layer thickness. Inkjetnano-imprinting approaches can be used to deposit different types ofmaterials across a given substrate simultaneously, and can be used toproduce variable thickness materials in different areas of a singlesubstrate simultaneously. This may be beneficial to PBPE structures,particularly when they are combined in a single substrate with moreconventional diffractive structures which may require other materialsand/or thicknesses of resist.

The liquid crystal layers deposited by jet technology can be cured usingUV curing, thermal methods, freezing, annealing and other methods. Theimprint template can include complex groove geometries (e.g., grooveswith multiple steps, gratings with different orientations, etc.). Liquidcrystal devices manufactured using the methods described herein caninclude liquid crystal layers comprising gratings with differentorientations and different PBPE structures.

The manufacturing methods using inkjet technology described herein canalso be configured to manufacture polarizers having increasedtransmissivity and/or wave plates comprising subwavelength featuresand/or metamaterials. These and other aspects are discussed in detailbelow.

FIG. 9A illustrates an embodiment of a method of fabricating a liquidcrystal device, preferably using inkjet technology. In the embodiment ofthe method illustrated in FIG. 9A, a layer 2000 b of liquid crystalmaterial is deposited on a substrate 2000 a, e.g., using inkjettechnology, as shown in panel (i). The liquid crystal material caninclude a doped or an un-doped liquid crystal material. In variousembodiments, the liquid crystal material can be a polymer stabilizednematic liquid crystal material. The substrate 2000 a can include glass,plastic, sapphire, a polymer or any other substrate material. The layer2000 b of the liquid crystal material can have a thickness between about20 nanometers and 2 microns. In some embodiments, the layer 2000 b ofthe liquid crystal material can have a thickness between about 0.5microns and about 10 microns.

The layer 2000 b of the liquid crystal material can be imprinted with animprint pattern 2000 c including wavelength and sub-wavelength scalesurface features, as shown in panel (ii). The surface features caninclude PBPE structures that can directly manipulate the phase of theincoming light. Without any loss of generality, a PBPE structure can bethought of as a type of polarization grating structure. In variousembodiments, the imprint pattern 2000 c can include an array of groovescomprising PBPE structures. The array of grooves can form a liquidcrystal grating structure that can have high diffraction efficiency andlow sensitivity to incident angle. The grooves can have a depth betweenabout nm and about 1 micron and a width between about 20 nm and about 1micron. In some embodiments, the grooves can have a depth between about100 nm and about 500 nm and a width between about 200 nm and about 5000nm. In some embodiments, the grooves can have a depth between about 20nm and about 500 nm and a width between about 10 nm and about 10 micron.The PBPE structures can include sub-wavelength patterns that encodephase profile directly onto the local orientation of the optical axis.The PBPE structures can be disposed on the surface of the liquid crystalgrating structures. The PBPE structures can have feature sizes betweenabout 20 nm and about 1 micron. In some embodiments, the PBPE structurescan have feature sizes between about 10 nm and about 200 nm. In someembodiments, the PBPE structures can have feature sizes between about 10nm and about 800 nm. In various embodiments, an underlying PBPEstructure can be used as an alignment layer for volumetric orientationof LC. The volumetric component in this case happens automatically, asthe LCs naturally align themselves to the alignment layer. In anotherembodiment, it may be desirable to differentially align multiple layerscontaining PBPE alignment and LC layers, to change diffractionproperties of the system as a composite—for example to multiplexmultiple wavelength operation since each sub-layer would act on only aselect subset of wavelengths.

In various embodiments, the imprint pattern 2000 c can include a simplegeometric pattern, such as, for example, a plurality of grooves or morecomplicated pattern such as multi-tier geometry including a plurality ofgrooves and recesses as shown in FIG. 9B. In various embodiments, theimprint pattern 2000 c can include a plurality of imprint layers, eachimprint layer including a different imprint pattern as shown in FIG. 9C.In the imprint pattern shown in FIG. 9C, the imprint layers 2000 c-1,2000 c-2 and 2000 c-3 include a plurality of grooves with progressivelydecreasing space between adjacent grooves. In various embodiments, theimprint pattern can include patterns such as chevron, spirals, arcs,etc. The imprint pattern can be fabricated on a semiconductor materialor other structure using methods such as e-beam lithography or otherlithography methods.

Referring to FIG. 9A, the layer 2000 b of the liquid crystal material isaligned to the imprinted pattern. The spaces between adjacent groovescan be filled with a material 2000 d. In some embodiments, fillingmaterial may comprise a transparent material having a lower refractiveindex less than the refractive index of the liquid crystal material, asshown in panel (iii). Such a configuration can be used, for example, ina waveguide structure. In this manner a high refractive index differencecan be obtained between the liquid crystal grating structures and itssurrounding such that the liquid crystal gratings can have highdiffraction efficiency. As mentioned above, the PBPE LC grating may bemade with a material-to-air interface, a resist-to-air interface,resin-to-air interface or liquid crystal material-to-air interface,where air is the low index “material”. However, in some cases it may bedesirable to place another layer of material on top of the priorpatterned layer, possibly in intimate contact, and in this case it maybe desirable to dispense and planarize a low-index curable resin thatpreserves the differential index of refraction between PBPE structures,but that also provide a laminate-able layer above. In variousembodiments, the liquid crystal gratings can be configured as Braggliquid crystal gratings. In various embodiments, the layer of lowrefractive index material 2000 d can be configured as a planarizationlayer. In such embodiments, the layer of low refractive index material2000 d can be configured to be planarized by another imprint pattern2000 e, as shown in panel (iv).

FIG. 9D illustrates another embodiment of a method of fabricating aliquid crystal device, preferably using inkjet technology. In theembodiment of the method illustrated in FIG. 9A, a layer 2000 f of aresist is deposited on a substrate 2000 a using inkjet technology, asshown in panel (i). The resist can include materials such as, forexample, organic and inorganic based imprint materials, resins orpolymers. For example, the resist can include materials disclosed inU.S. Pat. No. 8,076,386 which is incorporated by reference herein in itsentirety. In some embodiments, the resist layer 9F can have a thicknessbetween about 20 nm and about 1 micron. In some embodiments, the resistlayer 9F can have a thickness between about 10 nm and about 5 micron.The resist layer 2000 f can be imprinted with an imprint pattern 2000 cincluding volume and/or surface features, as shown in panel (ii). Alayer 2000 b of liquid crystal material can be disposed by inkjet on theimprinted resist layer 2000 f, as shown in panel (iii). The imprintedresist layer can serve to align the liquid crystal material as it is jetdeposited onto the imprinted resist layer 2000 f.

The liquid crystal devices fabricated using above described methods canbe cured using UV curing, thermal curing, freezing or other curingmethods.

Another embodiment of a method to fabricate liquid crystal devicesincludes imprinting a desired alignment structure in UV curable resistusing Jet and Flash™ Imprint Lithography (J-FIL); and dispensing aliquid crystal polymer formulation from inkjet. The liquid crystalpolymer can have a high solvent content, for example, to providesufficiently low viscosity to enable efficient egress through theinkjets. In various embodiments, the liquid crystal polymer can be in anisotropic state as it is dispensed. In some embodiments, the liquidcrystal polymer can be configured to align along the alignment structurein the resist by driving off the solvent. Additional liquid crystalpolymer layers can be disposed on top of the disposed liquid crystalpolymer layer by following the method described above. The formulationand the viscosity of the liquid crystal material in the solvent may alsobe adjusted to achieve rapid drying process for the dispensed liquidcrystal materials.

FIGS. 9E-9H illustrate embodiments of liquid crystal gratings fabricatedusing the methods described above. FIG. 9E illustrates a single layerliquid crystal grating including PBPE structures that have highdiffraction efficiency, high wavelength sensitivity and low sensitivityto incident angle. The liquid crystal gratings illustrated in FIG. 9Ecan be manufactured using the process depicted in FIG. 9A. For example,a liquid crystal polymer LCP1 can be deposited on a substrate and animprint template can be used to imprint a pattern on the liquid crystalpolymer LCP1 such that the molecules of the liquid crystal polymer LCP1are self-aligned to the imprinted pattern. The pattern can include ametasurface (e.g., PBPE structures). FIG. 9F illustrates a liquidcrystal grating including PBPE structures that have high diffractionefficiency, high wavelength sensitivity and low sensitivity to incidentangle. In the embodiment illustrated in FIG. 9F, the liquid crystalgratings can be manufactured using the process depicted in FIG. 9D. Forexample, an alignment layer comprising a polymer (e.g., a resist or aresin) can be deposited on a substrate and an imprint template can beused to imprint a pattern on the polymer. A layer of liquid crystalmaterial is deposited on the alignment layer such that the molecules ofthe liquid crystal layer are aligned to the pattern imprinted on thealignment layer. The pattern can be part of a metasurface (e.g., PBPEstructures). In various embodiments, PBPE structure of the first liquidcrystal layer (LCP1) can serve as the alignment structure for the secondliquid layer (LCP2).

FIG. 9G illustrates a three layer liquid crystal grating including PBPEstructures that have high diffraction efficiency, high wavelengthsensitivity and low sensitivity to incident angle. The multi-layerliquid crystal gratings can be manufactured using the processes depictedin FIG. 9A or 9D. For example, using the process of FIG. 9D, themulti-layer liquid crystal gratings illustrated in FIG. 9G can bemanufactured by aligning the molecules of a first liquid crystal layer(LCP1) using a first alignment layer comprising a first imprint patterndeposited on the substrate, aligning the molecules of a second liquidcrystal layer (LCP2) using a second alignment layer comprising a secondimprint pattern deposited on the first alignment layer and aligning themolecules of a third liquid crystal layer (LCP3) using a third alignmentlayer comprising a third imprint pattern deposited on the secondalignment layer. In some embodiments, the process of FIG. 9A may beutilized to form one or more of the first, second, and third liquidcrystal layers have aligned liquid crystal molecules (LCP1, LCP2, andLCP3, respectively). In such embodiments, each of LCP1, LCP2, and LCP3may be formed by imprinting a pattern in a liquid crystal layerdeposited over the substrate. The imprinting may be accomplished usingan imprint template having a pattern that causes the liquid crystalmolecules to align to the pattern. The imprint template may subsequentlybe removed and a filler may be deposited into the gaps left by theimprint template removal.

With continued reference to FIG. 9G, the first, second and third imprintpatterns can each be a metasurface (e.g., PBPE structures). The first,second and third imprint patterns can be different such that eachimprint pattern is configured to selectively diffract/redirect differentwavelengths of light in an incident beam to couple each of the differentwavelengths in one or more waveguides. In some embodiments, thedifferent wavelengths of light in an incident beam can be coupled intothe one or more waveguides at the same angle. However, in some otherembodiments, as discussed below, the different wavelengths of light inan incident beam can be coupled into the one or more waveguides atdifferent wavelengths. In some other embodiments, the PBPE structure ofthe first liquid crystal layer (LCP1) can serve as the alignmentstructure for the second liquid layer (LCP2) which in turn can serve asthe alignment structure for the third liquid layer (LCP3). Theembodiment illustrated in FIG. 9G can include different PBPE structuressuch that different wavelengths of light in an incident beam of lightare diffracted or redirected at different output angles such that theyare spatially separated. In various embodiments, the incident beam oflight can be monochromatic or polychromatic. Conversely, the multi-layerliquid crystal structure can be used to combine different wavelengths oflight as illustrated in FIG. 9H.

FIG. 9I illustrates a cross-section of a resist layer imprinted with animprint pattern illustrated in FIG. 9B.

As discussed above, the liquid crystal layer can be formed with avariety of materials. For example, in some embodiments, an acrylateliquid crystal formulation can be disposed over the polymer alignimprint structure using inkjet and imprint technology. Acrylatecomposition can facilitate stacking different liquid crystal layers ontop of each other that can adhere to each other without adhesive layersthereby making process simpler. Different liquid crystal layers can bestacked to achieve a desired effect, for example, the desiredpolarization, diffraction, steering, or dispersion effect.

The method described above can be used to fabricate liquid crystalpolarization gratings and patterned guiding layers using linearsubmasters with jet dispensing technology (e.g., J-FIL). Differentliquid crystal grating structures can be fabricated by combiningstructure with different shapes, orientations, and/or pitches. Thisprocess is described in more detail with reference to FIG. 9J whichillustrates a first imprint structure having discrete droplets orsections that are oriented along a first direction and a second imprintstructure having discrete droplets or sections that are oriented along asecond direction. The discrete droplets or sections of the first and thesecond imprint structures can be dispersed using inkjet technology. Thediscrete droplets or sections of the first and the second imprintstructures can merge or not merge in different embodiments. The discretedroplets or sections in the first and the second imprint structures canbe combined to produce an imprint structure with discrete droplets orsections having different orientations. Liquid crystal material can bedisposed on the combined imprint pattern to produce liquid crystalgratings with molecules aligned along different orientations. Thedifferent orientations of the separate sections together can produce amore complex grating pattern, similar, for example, to that of a PBPE,in the aggregate.

The inkjet and imprint methods discussed herein can be used to fabricateother optical elements such as waveguide plates, optical retarders,polarizers, etc. For example, a polarizer that is more transparent thanexisting polarizers can be fabricated using the methods describedherein. The method includes disposing a transparent or substantiallytransparent material that is patterned such as a polymer imprint anddepositing a polarizer material, such as, for example, an iodinesolution containing dichroic dye. The method includes imprinting apattern on the transparent polymer. The pattern can be linear grooves,chevrons, spirals, arcs, or any other simple or complicated pattern. Forexample, the pattern can be a periodic linear grating structure. Thepolarizer material can then be deposited on the patterned transparentpolymer using the jet technology (such as, for example, J-FIL) describedabove, imprint planarization or by spin coating. FIGS. 9K and 9Lillustrate different polarizer configurations that can be fabricatedusing the methods described above. The polarizers fabricated using thetechnology described herein can be more transparent than existingpolarizers. Such a component may be useful for devices that utilize lowextinction ratio polarizers such as a waveguide stack for head mounteddisplay eyepieces for augmented and virtual reality as describedelsewhere herein.

Subwavelength scale grating structures can induce birefringence inmaterials. For example, single dimensional grating can act as artificialnegative uniaxial materials whose optical axes are parallel to thegrating vector. Such birefringence can be referred to as formbirefringence. Accordingly, substrates including subwavelength scalegrating structures can function as wave plates. The amount ofretardation provided by substrates including subwavelength scale gratingstructures can depend on the dimension (e.g., height, width, pitch,etc.) of the grating patterns as well as the material refractive index.For example, a material with higher index comprising a pattern ofsubwavelength scale features can provide higher retardation than amaterial with lower index comprising a similar pattern of subwavelengthscale features. Inkjet and imprint technology, such as, for example,J-FIL allows high throughput Ultra Violet Nano-Imprint Lithography(UV-NIL) patterning capabilities with very low waste of material overany defined area. Inkjet and imprint technology, such as, for example,J-FIL can also facilitate repeated stacking of imprinted layers. Imprintlayers (single or multi-layered) with such subwavelength scale gratingstructures with or without varying geometry/orientation can providevarying degrees of phase-shift. Embodiments of patterned birefringentmaterials can enhance thin film integration capabilities in variousoptical applications.

The polarization of light output from substrates including subwavelengthscale grating structures can depend on the orientation, shape and/orpitch of the subwavelength scale grating structures. Embodiments of waveplates including subwavelength scale grating structures can also befabricated using the inkjet and imprint methods described herein. FIG.9M illustrates an embodiment of a waveguide plate 2005 having a lightentrance surface 2006 and a light exit surface 2007. The waveguide plate2005 can include a plurality of subwavelength scale grating featureswith varying shapes, orientations and/or pitches such that incidentunpolarized light is output as a polarized light. In variousembodiments, the wave plate 2005 can include multiple stacks of thintransparent films 2009 a, 2009 b and 2009 c that are imprinted withsubwavelength scale grating features with varying shapes, orientationsand/or pitches. The grating features can be imprinted on the transparentfilms using an imprint template as shown in FIG. 9C. In variousembodiments, the transparent films 2009 a, 2009 b and 2009 c cancomprise imprintable resists having refractive index between about 1.45and 1.75. The polarization of the light output from a multilayerstructure can depend on the shapes, orientations and/or pitches of thegrating structures as well as refractive index difference between thedifferent layers. For the embodiment illustrated in FIG. 9M, incidentunpolarized light is converted to right circularly polarized light bythe waveguide plate 2005. In other embodiments, the waveguide plate canbe configured to provide linearly polarized light, left circularlypolarized light or light with any other polarization characteristic.

It is contemplated that the innovative aspects may be implemented in orassociated with a variety of applications such as imaging systems anddevices, display systems and devices, spatial light modulators, liquidcrystal based devices, polarizers, wave guide plates, etc. Thestructures, devices and methods described herein may particularly finduse in displays such as wearable displays (e.g., head mounted displays)that can be used for augmented and/or virtually reality. More generally,the described embodiments may be implemented in any device, apparatus,or system that can be configured to display an image, whether in motion(such as video) or stationary (such as still images), and whethertextual, graphical or pictorial. It is contemplated, however, that thedescribed embodiments may be included in or associated with a variety ofelectronic devices such as, but not limited to: mobile telephones,multimedia Internet enabled cellular telephones, mobile televisionreceivers, wireless devices, smartphones, Bluetooth® devices, personaldata assistants (PDAs), wireless electronic mail receivers, hand-held orportable computers, netbooks, notebooks, smartbooks, tablets, printers,copiers, scanners, facsimile devices, global positioning system (GPS)receivers/navigators, cameras, digital media players (such as MP3players), camcorders, game consoles, wrist watches, clocks, calculators,television monitors, flat panel displays, electronic reading devices(e.g., e-readers), computer monitors, auto displays (including odometerand speedometer displays, etc.), cockpit controls and/or displays,camera view displays (such as the display of a rear view camera in avehicle), electronic photographs, electronic billboards or signs,projectors, architectural structures, microwaves, refrigerators, stereosystems, cassette recorders or players, DVD players, CD players, VCRs,radios, portable memory chips, washers, dryers, washer/dryers, parkingmeters, head mounted displays and a variety of imaging systems. Thus,the teachings are not intended to be limited to the embodiments depictedsolely in the Figures, but instead have wide applicability as will bereadily apparent to one having ordinary skill in the art.

Various modifications to the embodiments described in this disclosuremay be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other embodiments withoutdeparting from the spirit or scope of this disclosure. Thus, the claimsare not intended to be limited to the embodiments shown herein, but areto be accorded the widest scope consistent with this disclosure, theprinciples and the novel features disclosed herein. The word “exemplary”is used exclusively herein to mean “serving as an example, instance, orillustration.” Any embodiment described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otherembodiments. Additionally, a person having ordinary skill in the artwill readily appreciate, the terms “upper” and “lower”, “above” and“below”, etc., are sometimes used for ease of describing the figures,and indicate relative positions corresponding to the orientation of thefigure on a properly oriented page, and may not reflect the properorientation of the structures described herein, as those structures areimplemented.

Certain features that are described in this specification in the contextof separate embodiments also can be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment also can be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flow diagram. However, other operations thatare not depicted can be incorporated in the example processes that areschematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the embodiments describedabove should not be understood as requiring such separation in allembodiments, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other embodiments are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results.

Various example embodiments of the invention are described herein.Reference is made to these examples in a non-limiting sense. They areprovided to illustrate more broadly applicable aspects of the invention.Various changes may be made to the invention described and equivalentsmay be substituted without departing from the true spirit and scope ofthe invention. In addition, many modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention. Further, as will be appreciated by those with skill in theart that each of the individual variations described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinventions. All such modifications are intend22ed to be within the scopeof claims associated with this disclosure.

The invention includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the end user. In other words,the “providing” act merely requires the end user obtain, access,approach, position, set-up, activate, power-up or otherwise act toprovide the requisite device in the subject method. Methods recitedherein may be carried out in any order of the recited events which islogically possible, as well as in the recited order of events.

Example aspects of the invention, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present invention, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. The samemay hold true with respect to method-based aspects of the invention interms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference toseveral examples optionally incorporating various features, theinvention is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the invention. Variouschanges may be made to the invention described and equivalents (whetherrecited herein or not included for the sake of some brevity) may besubstituted without departing from the true spirit and scope of theinvention. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present invention is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

What is claimed is:
 1. A display system comprising: an injection deviceconfigured to output a multiplexed light stream that includes a firstlight stream having at least one first light property and a second lightstream having at least one second light property that is different fromthe at least one first light property; and a waveguide comprising one ormore in-coupling optical elements that are arranged to receive at leasta portion of the multiplexed light stream, wherein the one or morein-coupling optical elements are configured to selectively in-couple,into the waveguide, the first light stream having the at least one firstlight property while being transmissive to the second light streamhaving the at least one second light property, and wherein the one ormore in-coupling optical elements comprise one or morePancharatnam-Berry Phase Effect (PBPE) structures.
 2. The display systemof claim 1, wherein the at least one first light property includes afirst polarization state and the at least one second light propertyincludes a second polarization state that is different from the firstpolarization state.
 3. The display system of claim 1, wherein the atleast one first light property includes a first wavelength and the atleast one second light property includes a second wavelength that isdifferent from the first wavelength.
 4. The display system of claim 1,wherein the at least one first light property includes a firstpolarization state and a first wavelength, and the at least one secondlight property includes a second polarization state different from thefirst polarization state and a second wavelength different from thefirst wavelength.
 5. The display system of claim 1, further comprising:a second waveguide comprising one or more second in-coupling opticalelements that are arranged to receive at least a portion of themultiplexed light stream, wherein the one or more second in-couplingoptical elements are configured to selectively in-couple, into thesecond waveguide, the second light stream having the at least one secondlight property while being transmissive to the first light stream havingthe at least one first light property, and wherein the one or moresecond in-coupling optical elements comprise one or more second PBPEstructures.
 6. The display system of claim 5, wherein the secondwaveguide is configured to output light with a different level ofwavefront curvature than the waveguide.
 7. The display system of claim5, wherein the one or more in-coupling optical elements and the one ormore second in-coupling optical elements at least partly overlap, asviewed from an output end of the injection device.
 8. The display systemof claim 1, wherein the one or more in-coupling optical elements areswitchable between transmissive and actively light redirecting states.9. The display system of claim 1, wherein the one or more in-couplingoptical elements are formed on a surface of the waveguide.
 10. Thedisplay system of claim 1, wherein the one or more in-coupling opticalelements are formed in the waveguide.
 11. The display system of claim 1,wherein the injection device is configured to simultaneously output boththe first light stream and the second light stream toward the waveguide.12. The display system of claim 1, wherein the injection device isconfigured to output the first light stream and the second light streamat different times toward the waveguide.
 13. The display system of claim1, wherein the waveguide further comprises one or more out-couplingelements configured to output, from the waveguide, at least a portion ofthe in-coupled light that is propagating in the waveguide.
 14. Thedisplay system of claim 1, wherein the waveguide further comprises atleast one of an exit pupil expander or an orthogonal pupil expanderconfigured to increase dimensions of an eye box.
 15. The display systemof claim 1, wherein the injection device includes a scanning opticalfiber.
 16. The display system of claim 1, wherein the injection devicecomprises a light modulating device.
 17. The display system of claim 1,wherein the one or more in-coupling optical elements comprise a liquidcrystal material.
 18. The display system of claim 1, further comprisingan eyepiece that includes the waveguide, wherein the display system is ahead-mountable display system.